Bug 220238 - sys/dev/tws/tws.c: A possible sleep-under-mutex bug in tws_init_reqs
Summary: sys/dev/tws/tws.c: A possible sleep-under-mutex bug in tws_init_reqs
Status: New
Alias: None
Product: Base System
Classification: Unclassified
Component: kern (show other bugs)
Version: CURRENT
Hardware: Any Any
: --- Affects Only Me
Assignee: freebsd-bugs mailing list
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2017-06-24 03:16 UTC by Jia-Ju Bai
Modified: 2017-06-24 03:16 UTC (History)
0 users

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Description Jia-Ju Bai 2017-06-24 03:16:34 UTC
The driver may sleep under a mutex, and code path is:
tws_init_reqs [line 684: acquire the mutex]
tws_init_reqs [line 685]
  bus_dmamap_create(BUS_DMA_WAITOK) [line 687] --> may sleep

The possible fix of this bug is to replace the "BUS_DMA_WAITOK" in bus_dmamap_create with "BUS_DMA_NOWAIT".

This bug is found by a static analysis tool written by myself, and it is checked by my review of the FreeBSD code.